Herein we present a study using the density functional theory in periodic systems to describe the interaction of carbon fiber ultramicroelectrodes during the detection of the dihydroxybenzene isomers: catechol (CT), resorcinol (RS), and hydroquinone (HQ). We used graphene as the surface model in the conformations: carbon basal plane, zig-zag, and armchair edges. We modeled the surface models functionalized with oxygenated groups. We predicted chemisorption for the oxidized form of RS when the COOH group is present in the armchair edge. Also, the susceptibility of the RS to form dimers and trimers bonded to the electrode surface. Experimentally, the electrooxidation of RS showed inactivation of the ultramicroelectrode, which can be explained considering the chemisorptions mentioned above and the formation of no-electroactive polymers. In the case of the other two molecules (CT and HQ), the model describes favorable interaction energies with the electrode; none of them as strong as RS, thus, experimentally, we did not see affections to the electrochemical responses, and we could measure a well-defined steady-state current at different concentrations of these molecules. Furthermore, the characteristic half-wave potential (E1/2) of the isomers ensured their detection and quantification in single or mixed solutions in concentrations from 40 μM to 1 mM.